There are a myriad of different water purification systems currently available and in use. Depending on the particular material being treated, certain technologies become advantageous.
In filtration, liquid passes through a filtration medium. This can be accomplished through a number of ways such as the use of pressure to force the liquid through the filtration medium, the use of a vacuum to suck the material through a filtration medium or means such as capillary action. Settling tanks are also used as a source of water purification allowing suspended particulate matter to fall to the bottom allowing the cleaner water to remain towards the top.
One type of settling tank and filtration system which uses a vacuum to remove liquid and separate it from associated particulate matter is discussed in U.S. Pat. No. 5,000,846, the disclosure of which is incorporated herein by reference. This discloses a system to remove relatively purified liquid from a settling tank and to allow particulate matter to settle to the bottom of the tank. The settled particulate matter as indicated must still be removed.
This could be simply pumped down the drain. But this is often inappropriate due to environmental regulations. To separate the liquid from this particulate matter, a separate filtration system is needed.
There are many known separation systems. For example Traller U.S. Pat. No. 4,397,745 discloses a pressurized system, Glasby U.S. Pat. No. 2,913,120 discloses a vacuum delivery with gravity filtration and Paine U.S. Pat. No. 2,533,395 discloses a pressurized system. Anctsberger U.S. Pat. No. 3,504,798 and Lott U.S. Pat. No. 4,871,454 both disclose vacuum systems and Johnston U.S Pat. No. 2,714,349 discloses a combination of these.
The pressurized systems are particularly troublesome. The increased pressure requires filtration vessels which are stronger and therefore more expensive. Gravity filtration systems are less efficient. Vacuum systems are more preferred, but suffer from the disadvantage that they require a separate vacuum pump to operate.